This subproject is one of many research subprojects utilizing the resources provided by a Center grant funded by NIH/NCRR. The subproject and investigator (PI) may have received primary funding from another NIH source, and thus could be represented in other CRISP entries. The institution listed is for the Center, which is not necessarily the institution for the investigator. The goal of this project is to examine the hypothesis to see whether youth with cocaine or amphetamine dependence (who are in treatment) are more impulsive than control subjects. The researchers also hope to determine the underlying brain abnormalities that exist in people with cocaine or amphetamine abuse as measured by fMRI and GABA spectroscopy.